The present application relates to systems and methods for automating datacenter data replication for disaster recovery, and more particularly to a user-interface driven system and method for configuring eXtended Remote Copy (XRC) and Flashcopy for comprehensive data recovery.
In a z/OS (mainframe) environment, a disaster recovery solution is done at the DASD (Direct Access Storage Device) level. For every primary DASD volume, a target DASD volume is configured for replicating the primary DASD volume. There are multiple forms of replication, synchronous and asynchronous, and multiple z/OS technologies to perform this replication.
Peer to Peer Remote Copy or PPRC is a protocol to replicate a storage volume to another control unit in a remote site. Synchronous PPRC causes each write to the primary volume to be performed to the secondary as well, and the input/output (I/O) is only considered complete when update to both primary and secondary have completed. Asynchronous PPRC will flag tracks on the primary to be duplicated to the secondary when time permits. PPRC can be used to provide very fast data recovery due to failure of the primary site. In IBM zSeries computers with two direct access storage device (DASD) control units connected through dedicated connections, PPRC is the protocol used to mirror a DASD volume in one control unit (the primary) to a DASD volume in the other control unit (the secondary). In the IBM SAN Volume Controller PPRC is used to mirror a virtualized storage volume to remote (or the same) cluster.
Extended Remote Copy or XRC is an IBM zSeries and System z9 mainframe computer technology for data replication. It combines supported hardware and z/OS software to provide asynchronous replication over long distances. XRC is complementary to IBM's Peer to Peer Remote Copy (PPRC) service, which is designed to operate either synchronously or asynchronously over shorter distances. XRC as a z/OS copy services solution can be compared to Global Mirror for ESS, which is a controller-based solution for either the open systems or z/Series environments. Both Global Mirror for ESS (Asynchronous PPRC) and XRC (Global Mirror for z/Series) are asynchronous replication technologies, although their implementations are somewhat different. Extended Remote Copy or XRC is now known as Global Mirror for z/Series (XRC). XRC is a z/Series asynchronous disk mirroring technique which is effective over any distance. XRC keeps the data time consistent across multiple ESS (Enterprise Storage Server) or HDS (Hitachi Data Systems) disk subsystems at the recovery site. XRC functions as a combination of disk (IBM ESS or HDS licensed) Microcode and application code running on a z/Series host and provides a recovery point that is time consistent across multiple disk subsystems. The host component of the software is called the System Data Mover or SDM. The SDM ensures that no dependent writes are made out of sequence and data residing on the secondary volumes will always provide a time consistent copy of the primary volumes being mirrored.
While these technologies perform active replication, meaning data is being mirrored constantly, a point-in-time technology called Flashcopy is also used. Flashcopy is responsible for creating a point-in-time copy of a DASD volume, to a target DASD volume, such that the target volume can become instantly available for both read and write use. In some instances, this Flashcopy function is utilized to build out a disaster recovery datacenter, along with a stand-in environment.
All DASD volumes need to become replicated across all three (3) sites, and also part of appropriate Flashcopy groups in order to maintain a complete and consistent disaster recovery solution. Management of the replication methods and configurations across all three (3) sites for every individual DASD device is a monumental task, and validating configurations prior to putting them into production is essential in order to prevent DASD volumes from being missed from replication that would result in lost data in the event of a real disaster.